Article

Servo-Electric
Punching, Bending Fuels Productivity Push

In 1922—three generations ago—Jim Morroni founded Electric Equipment & Engineering Co. (EEE), in Denver, CO, as a small firm selling motors and electrical systems. Today, the Morroni-family-owned business has evolved into leading manufacturer of power-distribution and transfer systems in all shapes and sizes, from 200- to 4000-A capacity. Among its products: transfer switches, integrated load centers, power-distribution switchgear and circuit-breaker motor operators.

As an integrated manufacturer looking to keep sheetmetal fabrication as an inhouse core competency, the first fabrication machines installed at EEE were two single-station punch presses, which served the company well for many years. More recently, to meet rapidly growing demand for just-in-time deliveries, EEE’s Greg and Tim Morroni went in search of more productive fabrication equipment. In 1999, the firm invested in a Finn-Power P5 hydraulic turret punch press; in 2000 it added a Finn-Power F5 hydraulic turret punch press.

Continuous Improvement in the Fab Shop

EEE’s newest turret punch press, a servo-electric model, offers programmable position and speed of the punch and die—one setup can handle punching, nibbling, cutting, forming (to 0.63 in. high), marking, bending and tapping. Inset: The large work chute of the press allows quick removal of parts as large as 19.6 x 19.6 in.

Last but not least, early in 2009 the firm added an E5 Compact servo-electric turret punch press, which offers programmable position and speed of the punch and die—one setup can handle punching, nibbling, cutting, forming (to 0.63 in. high), marking, bending and tapping.

The punching process of the E5 combines servo-electric technology with mechanical power transmission, enabling strict punch control. A servomotor together with a lead screw moves a roll that in turn moves the ram by means of a guiding surface. Punching and forming strokes are based on horizontal movement, made by a servo motor, converted into vertical ram movement and transmitted to a punching or forming tool. In the punching mode, the roll moves horizontally over the top of the guiding surface, producing a punching stroke during each movement. The punching stroke is generated by a servomotor-driven mechanism.

The ram that moves the tool has numerically settable upper and lower limits (CNC-axis). For punching, EEE’s operator enters the tool length for each tool in the tool table. The CNC control determines the optimum stroke length according to tool length and sheet thickness. The stroke’s lower limit is based on the ram’s mechanical bottom position, fixed for punching. While forming, the upper and lower limits of the ram are freely set from its bottom position upwards

The Evolution of the Turret Punch Press

Today’s fabricators must be concerned not only with meeting current demands, but also must have the vision and strength to anticipate future challenges and changes in the marketplace. The equipment and tooling exist today to meet these challenges. The trick of course is to choose wisely.Today’s turret press offers a great deal of flexibility to sheetmetal fabricators. Equipment and tooling manufacturers continue to develop new machines and tooling that improve accuracy and efficiency, and that help fabricators eliminate costly secondary operations while performing functions once thought impossibleThe latest generation of the precision servo-electric turret punch presses represents a growing trend in the industry. Their precise upper and lower ram movements help to create special flanges and forms, reducing the need for secondary operations. And, servo-electric turret presses minimize connection power and power consumption—recent tests prove that by using a creative combination of servo-electric technology and mechanical power transmission, a servo-electric turret press consumes less than one-third the amount of electric power of a comparable hydraulic turret press. Servo-electric turret punch presses also offer adaptive reduced ram speed, which supports numerous operations including the forming of louvers, knock outs and shear tabs, and also proves beneficial for embossing and part marking.Some of the latest turret-press models feature programmable clamp setting that automatically positions sheet clamps. The possibility of punching the clamps is eliminated, and programming is easier. And, when changing production from full size to small sheets, clamp settings can be made automatically without wasting operator time. Dead zones can be completely eliminated by using individual one-clamp movement while the other clamp holds the sheet. This allows 100 percent utilization of the material.

Punch stroke is numerically controlled by the CNC, which provides a fast and optimal stroke. The stroke position and speed are controlled by the CNC. With forming tools, EEE programs a lower ram speed, forming speed and positioning tolerance.

“We were pleasantly surprised by the increased accuracy of the servo-driven punch,” says Greg Morroni, adding that the increased accuracy of the E5 allowed the company to redesign a line of fabricated outdoor power boxes to eliminate welding.

“We used to outsource welding of the outdoor boxes,” he says, “which must fit perfectly together to make the boxes watertight. Over the last 10 years, the price we paid to outsource the welding had tripled. Now, thanks to the good fitup we get from the parts coming off of the E5, we can rivet the boxes together. The punched holes match perfectly, and in the end the redesign reduced our manufacturing cost for the boxes by 50 percent.”

Other features of the E5 noted by the Morroni brothers as helping them optimize throughput in their sheetmetal-fabrication operations:

• Individual tool holders that allow the company to design their own turret layouts. Any tooling style from Mate Precision Tooling or Wilson Tool Intl. can be installed in the turret, as well as up to 10 auto-index, forming, or Multi-Tool stations.

• EEE has five full-tonnage auto index stations on its machine, which precisely rotate the punch and die in their tool holders in 0.001-deg. programmable increments.

• EEE has four Multi-Tool stations to increase the number of tools available in a turret, reducing setup time and increasing productivity. Multi-Tool stations offer six, eight, 10, or 24 punch/die combinations in only one station, establishing a turret within a turret.

• Upforming operations to form louvers that allow air flow through EEE’s boxes have improved thanks to the machine’s capabilities to form to 0.63 in. height and 5-in. dia.

“Another advantage is that all of the dies are at the same height and there are more high-forming dies in the turret,” explains Tim Morroni, “reducing the risk of material damage and increasing machine uptime. We used to employ a single-station louver punch, which was significantly slower and more expensive to run than our upforming solution today.”

• The large work chute of the turret press allows the firm to remove large parts quickly from the machine—as large as 19.6 by 19.6 in.—which then drop onto a conveyor and exit the machine, reducing shaker parts and eliminating skeletons. “Today, we try to send as many parts as possible down the work chute,” adds Tim Morroni. “It eliminates the labor of shaking parts out and the parts are ready to bend. In addition, with no micro joints, I don’t have to worry about deburring or having them bump on the backgauge of the press brake.”

• The tapping feature of the E5 pays a big dividend to EEE. The company selected a six-station servo-driven tapping unit. Explaining its payback, Tim Morroni describes a motor-base part that has 40 tapped holes in three different sizes.

“On our old machine it would take 2.5 hr. to fabricate 24 parts,” he says. “On the E5, we can make 48 parts in just 25 min.”

Servo-Brake Accuracy Reduces Assembly Time

The final piece of equipment added to the EEE sheetmetal-fabrication shop was a servo-electric press brake, which Greg Morroni credits with improving the shop’s bending speed and accuracy.

“Our outlook for the future is pretty good,” concludes Morroni. “The telecommunications marketplace has dwindled, with fewer customers and fewer vendors. However, there are plenty of doors open to us, due to our ability to innovate and maintain manufacturing flexibly, which allows us to meet tight deadlines.” MF